Amplifying anti-flooding electrode to fabricate modular electro-fenton system for degradation of antiviral drug lamivudine in wastewater

Abstract

The advanced oxidation based on in-situ hydrogen peroxide production using carbon air cathode is very potential for wastewater treatment. However, catalyst flooding and complex assembly patterns are the bottleneck limiting the air cathode to the long-term and large-scale application. In this work, a novel anti-flooding air-breathing cathode (ABC) was prepared by a simple rolling-spraying method with relatively low price commercial materials. The novel method changed the morphology of gas diffusion layer as well as adjusted the hydrophobicity of air side of the catalyst layer. As a result, water-air distribution management was achieved and TPI disequilibrium was prevented. Compare with traditional ABC, the H2O2 yield and current efficiency (CE) of optimized anti-flooding ABC (ABC0.9) increased by 13.5% (941 ± 10 mg·L−1·h−1 with CE of 84% at 30 mA·cm−2), the material cost and fabrication time decreased by 10.1% (2.32 ¥·dm−2, ~0.36 $·dm−2) and 40%. Amplified ABC coupled with Ti/IrO2 anodes were integrated into a modular electrode used for H2O2generation. When the current density (j) increased from 10 to 30 mA·cm−2, the energy cost increased from 0.19 to 0.43 ¥·mol−1 H2O2 (from 0.03 to 0.07 $·mol−1 H2O2). The modular electrode was utilized in a 2 L pre-pilot scale reactor for antiviral drug lamivudine degradation by electro-Fenton (EF) process. 100% of lamivudine and 78.1% of total organic carbon (TOC) were removed within 60 min at 20 mA·cm−2. The susceptible sites on the lamivudine toward hydroxyl radicals were investigated and transformation products (TP) as well as degradation pathway were studied.